A so-called single-plate imaging apparatus, which is one of full-color imaging apparatuses, is suitable for a case of requiring size reduction and cost reduction of a configuration such as a consumer digital still camera (DSC) and a camera-equipped cell-phone. In the single-plate imaging apparatus, any of color filters for red (R), green (G), and blue (B) is provided on a photoelectric element, and an image signal of a plurality of colors is obtained from one two-dimensional imaging element by calculating sensitivity signals of lacking color components for each pixel position. A sensitivity level value for the lacking color component is generated by interpolation processing that uses known sensitivity level values at a target pixel and peripheral pixels therearound (for example, see Japanese Patent Application Laid-open No. 2001-197512).
Conventionally, in generating the sensitivity level value of the lacking color component, for example, a method is employed, in which a low-frequency component and a high-frequency component of image signals are extracted and added. Degradation of resolution is suppressed by the addition of the high-frequency component, so that it is possible to obtain a high-resolution image on which pixel interpolation processing is performed. However, in the case of requiring image processing that focuses on S/N (signal to noise ratio) more than the resolution, such as shooting under a low illumination environment, the high-frequency component may become a factor of S/N degradation. Moreover, when an image signal is converted from an ROB format into a YUV format to output, a color noise may be degraded due to the high-frequency component.